Arrangement for resistance transformation



W. BUSCHBECK 2,231,152 ARRANGEMENT FOR RESISTANCE TRANSFORMATION Feb.11,

Filed June 14, 1939 2 Sheets-Sheet l INVENTOR. WERR BUSCHBECK 1:

' ATTORNEY.

Feb. 11,

W. BUSCHBECK ARRANGEMENT FOR RESISTANCE TRANSFORMATION Filed June 14,1939 2 Sheets-Sheet 2 Ric/r W INVENTOR. WERNER BUJCHBECK ATTORNEY.

Patented Feb. 11, 1941 UNITED STATES PATENT OFFICE ARRANGEMENT FORRESISTANCE TRANSFORMATION tion of Germany Application June 14,1939,Serial No. 279,079 In Germany June 14, 1938 12 Claims.

In the high frequency field the problem often presents itself totransform to other values, resistances in a possibly simple mannerwhereby at the same time the requirement may have to be 5' fulfilled toconvert resistances symmetrical with respect to ground into those whichare unsymmetrical with respect to ground, and vice versa;

such as, for instance, at the symmetrical withdrawal of energy from apush-pull transmitterto be conducted on a grounded power cable, or atthe passage from such a cable to an antenna arrangement which issymmetrical with respect to ground. To achieve these ends, variousarrangements have already become known and have been proposed, such aswith quasi-stationary means aside from simple transformer circuits,called the Boucherot bridge (German Patent 603,816), then the 1/2reversing line with nonquasi stationary means (German Patent 568,559,corresponding to United States Patent No. 2,155,652, German Patent620,001), the symmetry providing loop (British Patent 433,506,corresponding to United States No. 2,127,088) and the blocking tank(United States Patent 2,131,108, Fig. 12).

In accordance with the invention, an arrangement is proposed furnishingwith simple means a transformation of 1:4 while retaining the symmetrybetween coupled circuits, and which renders possible a transfer ofenergy to the non-symmetrical line at the same time by utilizing anadditional arrangement. The latter possibility offers the advantage overthe said reversing line in that the tuning at wave change, etc., can becarried out in a much simpler way.

A more detailed description follows in conjunction with drawings,wherein Figs. 1, 1a, 2, 2a., 3 and 4 illustrate six differentembodiments of the invention. All of these figures illustrate a systemhaving an impedance transformation ratioof 1:4. Figs. 1 and 1a.illustrate arrangements wherein there is effected a transformation ofone symmetric or balanced potential into another symmetriq' or balancedpotential, while Figs. 2, 2a, 3 and 4 illustrate arrangements wherein asymmetric or balanced potential is transformed into an unbalanced orasymmetric potential. In these figures similar elements are representedby similar reference characters.

In-Fig. 1, two concentric lines L1 and L2, each having a wave resistance(i. e. surge impedance) equal to W ohms and having, for instance, an E.M. F. symmetrical with regard to ground are connected to a symmetryproducing loop which contrary to the known construction has in both legsinner conductors having at the same time potentials applied thereto. Atthe open end of the loop the inner conductors thereof are criss-crossconnected by means of wires I and 2 with the opposite outer conductors;a slide S movable over the outside of the conductors of the loop or avariable wattless resistance (1. e. reactance) at the open end of theloop permits of tuning for a blocking circuit. Since in this type ofcircuit each of the two concentric lines must be terminated by aresistance having the value W in order to obtain impedance matching,while the ends of the two lines are placed in parallel, however, thereappears at the output a resultant resistance of the value while at theinput side the lines are in series and there is a resistance equal to 2Wbetween the two inner conductors so that the entire arrangement will infact be transformed in the proportion 4:1 while retaining the symmetrywith respect to ground, whereby the absolute values of the waveresistances (surge impedances) can be chosen within wide limits bydimensioning-the lines accordingly. One disadvantage of Fig. 1 is thatradiation occurs from the external or outer conductors of the loop. Thisdisadvantage is overcome in Fig. 1a. wherein a surrounding tube Bprovides a high impedance to the flow of radio frequency energy over theouter conductors on both sides of A, B.

In Fig. la, the reactance formed by the surrounding metallic tube R andthe external conductors ofcables L1 and L2 is tuned by suitabledimensioning of the length between the terminals of the conductor andthe discs Sch connecting tube R to the external conductors. Said discsSch are displaceable for enabling tuning variation. In effect, each halfof the tube forms a blocking tank (M4 long as measured from disc Sch toA or B).

If it is desired to pass from the symmetrical state to thenon-symmetrical state, a simple symmetry producing loop may be connectedto the open end as shown in Fig. 2. It may hereby be suitable asactually shown in Fig. 2 to employ two separate loops I and 11 if thesecan be inserted in the line train between the source of E. M. F. and theload. But this is not necessary; since the compensation currents flow infact through the two loops in the opposite directions, these loops canbe placed above each other so that the tuning and the symmetricalcondition can be obtained at the same time with a single slide. Fig. 2suffers from the same disadvantage as Fig. 1, in that radiation occursfrom the outer conductors of the loop. It is clear that in actualconstructions the loops should in general be of the shielded type, i.e., in case of longer waves the loops can be of the wound type (Fig. 3)whereby suitably each tube part can be wound as such into a convenientcoil, while both coils are to be formed in the opposite sense in orderto reduce the exterior stray field. The arrangement of Fig. 3 isdescribed in more detail hereinafter. It is obvious that the E. M. F.and the load can be interchanged as in all such arrangements.

Fig. 4 shows another example of construction in accordance with theinvention. In this figure,

the arrangement of Fig. 1a is supplemented by a condenser C connected tothe points A and B for tuning the reactance, and also supplemented by aconcentric sleeve or blocking tank S. The two lines L1, L2 of the waveresistance 2W, forming in combination a line which is symmetrical withrespect to ground, terminate into branches and are in serted in asurrounding tube R such that the ends thereof which are connectedcrosswise with one another are situated closely opposite each other. Ifthe reactance formed by the surrounding tube R and the outer conductorsof the power cable is tuned for a blocking circuit (either by a suitabledimensioning of the length between the ends of the line and the slidablediscs Sch which connect the tub-e R with the outer conductors, or by thetuning of a parallel condenser C), a resistance placed between thepoints A, B and having the value W furnishes matching-on the two cablespassed around at the left side and right side, and the arrangement,therefore, furnishes a transformation of 4:1 while retaining symmetrywith respect to ground. The transit to the unsymmetrical state can berealized by means of the blocking tank S already proposed whoseinductance together with the already mentioned inductance can be tunedthrough short circuiting slider K and through condenser C which may alsobe represented suitably by a tubular parallel line with slidable shortcircuit bottom and whose length is above M4. The arrangement of Fig. 4can be simplified by omitting the electrically decoupled blocking tank Sand placing the asymmetric cable together with wave resistance W insideone arm of the surrounding tube R and connected to the power line of thewave resistance 2W which is passed towards the left side. Such ,anarrangement is shown in Fig. 2a. A similar thickening of the outerconductor of the cable extending towards the right side is hereby notrequired and not even appropriate, since with this measure only theinductance of the blockingpart at the right would be reduced so that inthis case the resultant wattless power of the entire blocking structurewould be increased. It would be possible to pass outside thetransformation structure by means of a tube surrounding the cablepassing to the right side and which would then form the outer casing ofthe unsymmetrical line outside the blocking tube R, whereby the outerconductor of the cable having the wave resistance 2W and passing aroundat the right side would form inside the blocking tube R the innerconductor of the line having the wave resistance W and beingunsymmetrical with respect to ground.

The arrangement according to Fig. 3 may be developed from thearrangement according to Fig. 2 with which it is electrically absoluteequiv- 'alent by imagining that the right half of II of Fig.

2 is folded back to the left half I, so that in each branch two parallelenergy lines exist. In order to place these two energy lines in a commontube, the tubes are parted in the center and one energy line runs in theupper external half of the tube while the other proceeds in the innerhalf of the tube. The symmetric line with wave resistance 4W beginningat the lower left-hand side proceeds in the two internal conductors Iand 2,

both of which then proceed in the lower sections of the two coiled loopbranches. The symmetric conductor with wave resistance W beginning atthe lower right-hand side, proceeds in conductor 3 which then runs inthe upper section of the left loop path. Conductors 2 and 3 areconnected to one another at the upper end of the left loop half and areconnected in common to the end of the external conductor of the rightloop half. Line I proceeding in the lower section of the right loop halfis connected at its top end to the end of the external conductor of theleft loop half. Short circuit bridge J of Fig. 2 is replaced in Fig. 3by sliding contacts J which may be displaced in their position on theexternal conductors of the two loop halves by rotating the mountingaxles H. This makes possible a tuning equivalent to the tuning of Fig. 2where a portion of the coiled loop halves is short-circuited.

What is claimed is:

1. In a high frequency transmission system, a loop formed by a pair ofcoaxial lines, the correspondingly located ends of which are adjacenteach other while the intermediate portions of said lines are spacedapart; a connection between the inner conductor of one line at one endand the adjacent outer conductor of the other line, and a connectionbetween the inner conductor of said last line at said same end and theadjacent outer conductor of said first line; a transmission line coupledto said loop at said last end; and a circuit balanced with respect toground connected to the coaxial lines at the other end.

2. In a high frequency transmission system, a loop formed by a pair ofcoaxial lines, the correspondingly located ends of which are adjacenteach other while the intermediate portions of said lines are spacedapart; a connection between the inner conductor of one line at one endand the adjacent outer conductor of the other line, and a connectionbetween the inner conductor of said last line at said same end and theadjacent outer conductor of said first line; a circuit balanced withrespect to ground coupled to said coaxial lines at said last end; and acircuit balanced with respect to ground connected to the coaxial linesat the other end.

3. In a high frequency transmission system, a loop formed by a pair ofcoaxial lines, the correspondingly located ends of which are adjacenteach other while the intermediate portions of said lines are spacedapart; a connection between the inner conductor of one line at one endand the adjacent outer conductor of the other line, and a connectionbetween the inner conductor of said last line at said same end and theadjacent outer conductor of saidfirst line; a circuit unbalanced withrespect to ground coupled to said coaxial lines at said lastend; and acircuit balanced with respect to ground connected to the coaxial linesat the other end.

4. In a high frequencytransmission system, a

loop formed by a pair of coaxial lines, the correspondingly located endsof which are adjacent each other while the intermediate portions: ofsaid lines are spaced apart; a connection between the inner conductor ofone line at one end and the adjacent outer conductor of the other line,and a connection between the inner conductor of said last line at saidsame end and the adjacent outer conductor of said first line; a variablecondenser connected across said connections; a transmission line coupledto said loop at said last end; and a circuit balanced with respect toground connected to the coaxial lines at the other end.

5. In a high frequency transmission system, a loop formed by a pair ofcoaxial lines, the correspondingly located ends of which are adjacenteach other while the intermediate portions of said lines are spacedapart; a connection between the inner conductor of one line at one endand the adjacent outer conductor of the other line; and a connectionbetween the inner conductor of said last line at said same end and theadjacent outer conductor of said first line; a transmission linedirectly connected to said loopat said last end; and a circuit balancedwith respect to ground connected to the coaxial lines at the other end.

6. A system in accordance with claim 1, including a strap movable overthe spaced apart outer conductors of the coaxial lines constituting theloop for tuning said loop.

7. In a high frequency transmission system, a loop formed by a pair ofcoaxial lines, the correspondingly located ends of which are adjacenteach other while the intermediate portions of said lines are spacedapart; a connection between the inner conductor of one line at one endand the adjacent outer conductor of the other line, and a connectionbetween the inner conductor of said last line at said same end and theadjacent outer conductor of said first line; another loop coupled tosaid first loop; a circuit balanced with respect to ground connected tothe coaxial lines of said first loop at the end thereof removed fromsaid connections; and a circuit unbalanced with respect to groundconnected to said other loop.

8. In a high frequency transmission system, a tuned circiut formed by apair of coaxial lines, the correspondingly located ends of which areadjacent each other while the intermediate portions of said lines arespaced apart; a connection between the inner conductor of one line atone end and the adjacent outer conductor of the other line, and aconnection between the inner conductor of said last line at said sameend and the adjacent outer conductor of said first line; a circuitbalanced with respect to ground connected to said tuned circuit at theend thereof removed from said connections; and a transmission line alsoconnected to said tuned circuit.

9. In a high frequency transmission system, a tuned circuit formed by apair of coaxial lines, the correspondingly located ends of which areadjacent each other while the intermediate portions of said lines arespaced apart; a connection between the inner conductor of one line atone end and the adjacent outer conductor of the other line, and aconnection between the inner conductor of said last line at said sameend and the adjacent outer conductor of said first line; and a pair ofcircuits in energy transfer relation coupled to said tuned circuit.

10. A system in accordance with claim 8, characterized in this that thelines of said tuned circuit are coiled.

11. In a high frequency transmission system, a loop formed by a pair ofcoaxial lines, the correspondingly located ends of which are adjacenteach other while the intermediate portions of said lines are spacedapart; a connection between the inner conductor of one line at one endand the adjacent outer conductor of the other line, and a connectionbetween the inner conductor of said last line at said same end and theadjacent outer conductor of said first line, said coaxial lines at saidend being arranged in substantially the same straight line; a tubularmetallic surface surrounding said lines for a portion on both sides ofsaid connections and tuned to provide a high impedance to currentstending to flow over the outer conductors of said coaxial lines; atwoconductor transmission line connected to said connections at saidlast end; and a circuit balanced relative to ground connected to thecoaxial lines at the other end.

12. In a high frequency transmission system, a loop formed by a pair ofcoaxial lines, the correspondingly located ends of which are adjacenteach other while the intermediate portions of said lines are spacedapart; a connection between the inner conductor of one line at one endand the adjacent outer conductor of the other line, and a connectionbetween the inner conductor of said last line at said same end and theadjacent outer conductor of said first line, said coaxial lines at saidend being arranged in substantially the same straight line; a tubularmetallic surface surrounding said lines for a portion on both sides ofsaid connections; slidable straps between said tubular surface and theouter conductors of said coaxial lines on both sides of said connectionsfor tuning the efiective length of said surface; a two-conductortransmission line connected to said connections at said last end; and acircuit balanced relative to ground connected to the coaxial lines atthe other end.

WERNER BUSCI-IBECK.

